George Sicherman: I have not found any 5x5 pentapent solutions, but we can use the 7 tetrapents to make two congruent 28-pents, providing that we use one of the tetrapents in both figures. This figure is unique, but the tiling on the left is not.

TheMetagrobologist Magazine

TheMetagrobologist Magazine is a very snazzy only magazine devoted to puzzles.

Mark J. P. Wolf (from my work-in-progress book, 101 Enigmatic Puzzles)
Within the new Short Form 1, there is a loophole; with just the right amount of income, you don’t owe any tax at all. Find the one income amount that will result in zero tax owed when the tax form below is filled out. (docx answer)

Recent Anagrams

Arlo Guthrie's The City of New Orleans = Steel light train confers "How are you?".
I Have No Mouth And I Must Scream = A dour time to humans vs. machine.
Captain America: The Winter Soldier = WARipedia historical reenactment.
American Institute of Bisexuality = Caution: extreme unsatisfiability.
Christopher Nolan films esoteric ~ techno-thriller for space mission.
Worst-Case Scenario Handbook = Coordinate Seahawks-Broncos.
Electrochemical fluorination = Lime in the coconut for all I care.
Blockbuster motion picture = Put trust in comic book rebel.
Money is the root of all evil = Some love the irony of it all.
Let's run it up the flagpole = Telling "put up for the sale."
Institutional researcher = "In the literature" narcosis.
"A Tribute to Heroes" = He's about to retire.
Hi, G. Washington! = How's it hanging?
Crimea votes to ~ act more soviet.
Interest group = Peers tutoring.

Heesch-2 Polyomino

Glenn Rhoads found the minimal Heesch 2 polyomino in his 2003 thesis "Planar Tilings and the Search for an Aperiodic Prototile". I haven't seen it elsewhere, so here's a picture:

Minimal Superpermutations

123412314231243121342132413214321 has all permutations of "1234", and is minimal. The shortest string for "12345" is unknown. These are called minimal superpermutations, and much harder to find than DeBruijn sequences.

Take 12 points around a square, with points in the corners and 4 points on each side. Join up the points with 6 lines, with no lines connecting points on the same side. The correct answer is 200 ways to do it. If mirror symmetries are removed, then there are 121 ways to do it.

MIT's Infinite Corridor was used to make a new folding record, breaking Britney Gallivan's paper folding record. I got her mentioned in the Numb3rs episode Identity Crisis.

No Four in a Plane

There are 38 ways to pick 13 points from a 5x5x5 grid so that no four points are in a plane. There is a unique solution for 8 points from 3x3x3, and 232 solutions for 10 points from 4x4x4. What are solutions for 6x6x6 and up?

Site Goals

Martin Gardner celebrates math
puzzles and
Mathematical Recreations. This site aims to do the same. If you've made
a good, new math puzzle, send it to ed@mathpuzzle.com.
My mail address is Ed Pegg Jr, 1607 Park Haven, Champaign, IL 61820.
You can join my moderated recreational mathematics email list at http://groups.yahoo.com/group/mathpuzzle/. My facebook page is at Ed Pegg Jr.

All material on this site is copyright 1998-2014 by Ed Pegg Jr. Copyrights of
submitted materials stays with the contributor and is used with permission.